JP6729697B2 - Wire saw device and work cutting method - Google Patents

Description

The present invention relates to a wire saw cutting technique, and relates to a wire saw device and a work cutting method applicable to a wafer cutting step of slicing a work, for example, a silicon semiconductor single crystal ingot into a wafer.

For example, in the field of semiconductor manufacturing, a plurality of silicon semiconductor wafers are obtained by thinly cutting a silicon semiconductor single crystal ingot pulled up by a single crystal pulling apparatus in a direction perpendicular to an axis by an inner peripheral blade slicer.

However, the recent tendency toward larger diameter semiconductor wafers makes it difficult to cut an ingot by a conventional inner peripheral blade slicer. Further, the cutting method using the inner peripheral blade slicer has a problem that the wafer is cut out one by one, which is inefficient and the productivity is poor.

Therefore, a cutting method using a wire saw (particularly, a multi-wire saw) has been receiving attention in recent years. This cutting method is performed by pressing a work against a wire row spirally wound between a plurality of main rollers (wire guides) and moving the wire while supplying slurry to a contact portion between the work and the wire. Is a method of cutting a work into a wafer (for example, Patent Document 1). With such a cutting method, a large number (for example, several hundreds) of wafers can be cut at one time.

Further, as in Patent Document 2, a vibrometer is attached to a holding portion of a grooved roller to detect disconnection, and as in Patent Document 3, a bearing housing of a reel bobbin or a bracket of the bearing housing is vibrated. There is a meter attached with a vibration sensor for detecting abnormal rotation of the reel bobbin.

Japanese Patent Laid-Open No. 11-156694 JP, 2013-035080, A JP, 2000-190196, A

However, in the cutting method using the wire saw as described above, when the work is cut in a state where the wire tension cannot be kept constant, and the wire is rough or abnormal vibration occurs, the Warp quality deteriorates. Can be seen. If the above-mentioned abnormality is noticed during cutting of the work and the apparatus is stopped for maintenance, the Warp quality is deteriorated due to the temperature change. In both cases, a large number of wafers are cut out at one time, which has a problem that a large number of defects are likely to occur.

The present invention has been made in view of the above-mentioned problems, and it is possible to determine the state where the tension of the wire is violent or the wire saw device is abnormally vibrated before cutting the work, and the work is cut from the work. It is an object of the present invention to provide a wire saw device and a work cutting method capable of preventing the quality deterioration of a broken wafer.

To achieve the above object, according to the present invention, a wire supply reel that extends a wire, a wire row formed by the wire spirally wound around a plurality of wire guides, and the wire A wire take-up reel that winds up the work, and a work holding portion that holds the work to be cut, and at least the work held by the work holding portion on the wire row that travels forward and backward repeatedly at least once. In a wire saw device that presses and cuts,
A wire saw device comprising: a vibration sensor attached to the work holding part; and a load cell for detecting the tension of the wire.

In such a case, before cutting the work, at least one of the tension of the wire detected by the load cell and the vibration detected by the vibration sensor is measured, and the measured value is used to determine whether the wire saw device is operating normally or not. It is possible to judge abnormality. Therefore, if the work is cut when it is determined that the wire saw device is normal, deterioration of the quality of the wafer cut from the work can be prevented.

Further, according to the present invention, there is provided a method for cutting a work using the wire saw device of the present invention,
Before the cutting of the work, the wire tension detected by the load cell and the vibration sensor are detected while the work is kept in contact with the wire and the wire is repeatedly run at least once forward and backward. A determination step of performing at least one of the vibrations of the wire saw and determining whether the wire saw device is normal or abnormal using the measured value.
A method of cutting a work, comprising a cutting step of cutting the work when the wire saw device is determined to be normal.

Since such a work cutting method uses the above-described wire saw device of the present invention, it is possible to judge whether the wire saw device is normal or abnormal before cutting the work. Then, when it is determined that the wire saw device is normal, the work is cut, so that it is possible to prevent deterioration of the quality of the wafer cut from the work.

At this time, in the determination step,
Performs control chart management using the measured value, determines that the wire saw device is abnormal when the measured value is outside the control value limit, and stops the wire saw device before cutting the workpiece, It is preferable to perform maintenance of the wire saw device and then cut the work until it falls within the control value limit.

In this way, by controlling the control chart, the state of the wire saw device can be grasped before cutting of the work, and by performing maintenance in the case of an abnormal state outside the control value limit, deterioration of the quality of the wafer cut from the work and It is possible to reduce the occurrence of defects due to deterioration of quality.

Further, according to the present invention, there is provided a method of cutting a work by using the wire saw device of the present invention, wherein the wire is at least moved forward and backward without cutting the work into contact with the wire. While repeatedly traveling more than once, confirm that the standard deviation of the tension of the wire detected by the load cell is 0.45 N or less and the vibration detected by the vibration sensor is 1.0 mm/sec or less. From the above, there is provided a method of cutting a work, which comprises cutting the work.

As described above, when the standard deviation of the wire tension is 0.45 N or less and the vibration is 1.0 mm/sec or less, it is determined to be normal, and the work is cut only when the normal is determined, The quality of the wafer cut out from the work can be more reliably prevented.

With the wire saw device of the present invention, at least one of the tension of the wire detected by the load cell and the vibration detected by the vibration sensor is measured before cutting the workpiece, and the measured value is used to determine whether the wire saw device is operating normally. Alternatively, it is possible to judge abnormality. Therefore, if the work is cut when it is determined that the wire saw device is normal, deterioration of the quality of the wafer cut from the work can be prevented.

Further, according to such a work cutting method using the wire saw device of the present invention, it is possible to judge whether the wire saw device is normal or abnormal before cutting the work. Then, when it is determined that the wire saw device is normal, the work is cut, so that it is possible to prevent deterioration of the quality of the wafer cut from the work.

It is the schematic which showed an example of the wire saw apparatus of this invention. It is process drawing which showed an example of the cutting method of the workpiece|work of this invention. FIG. 7 is a control chart of the wire tension variation σ during warm-up. Slices obtained when the workpiece is cut off when the wire tension variation σ during warm-up is outside the control value limit (a) abnormal (comparative example 1) and within the control value limit (b) normal (example 1) It is a graph which showed the average Warp quality of 25 goods. It is a control chart of the average value of the vibration amplitude at the time of warming up. When the average value of the vibration amplitude during warm-up is outside the control value limit (a) abnormal (comparative example 2) and within the control value limit (b) normal (example 2), when the work is cut It is a graph which showed the average Warp quality of 25 slices.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

As described above, in the cutting method using the wire saw device, when the work is cut in a state where the wire tension cannot be kept constant and is greatly disturbed or abnormal vibration occurs, the Warp quality is deteriorated. Can be seen. If the above-mentioned abnormality is noticed during cutting of the work and the apparatus is stopped for maintenance, the Warp quality is deteriorated due to the temperature change. In both cases, a large number of wafers are cut out at one time, which has a problem that a large number of defects are likely to occur.

Therefore, the present inventor has conducted earnest studies to solve such a problem. As a result, if the wire saw device is equipped with a vibration sensor attached to the part that holds the work and a load cell that detects the wire tension, before the cutting of the work, the wire tension detected by the load cell and the vibration sensor At least one of the detected vibrations can be measured, and the measured value can be used to determine whether the wire saw device is normal or abnormal.If it is determined that the wire saw device is normal, the work is cut. Then, it has been conceived that the deterioration of the quality of the wafer cut out from the work can be prevented. Then, the best mode for carrying out these was scrutinized to complete the present invention.

First, the wire saw device of the present invention will be described with reference to FIG. As shown in FIG. 1, a wire saw device 13 of the present invention includes a wire supply reel 1 for extending a wire 8 and a wire row formed by a wire 8 spirally wound around a plurality of wire guides 6. 9, a wire take-up reel 7 that winds the wire 8, and a work holding unit 10 that holds the work W to be cut, and the work holding unit is provided on the wire row 9 that travels at least once forward and backward. The work W held by 10 is pressed to perform cutting work. The wire saw device 13 includes a vibration sensor (vibrometer) 11 attached to the work holding unit 10 and a load cell 5 that detects the tension of the wire 8.

In the wire saw device 13, a wire 8 is wound in parallel from a wire supply reel 1 through a long roller 2, a traverser 3, and a plurality of pulleys P on a wire guide 6 at a predetermined pitch to form a wire row 9. The work W is cut by lowering the work W held by the work holding unit 10 onto the wire row 9. The wire 8 exiting the wire guide 6 passes through the plurality of pulleys P and the traverser 3 and is wound up on the wire winding reel 7.

In the wire saw device 13 of the present embodiment, the load cell 5 and the tension mechanism 4 are provided between the wire supply reel 1 and the wire guide 6, and between the wire guide 6 and the wire take-up reel 7, respectively. Based on the above, the tension of the wire 8 is controlled by the tension mechanism 4.

A vibration sensor 11 is attached to the work holding unit 10. The vibration sensor 11 can be configured, for example, by directly attaching the work W in the work holding unit 10 to a plate to which the work W is adhered and monitoring the vibration. The load cell 5 and the vibration sensor 11 are connected to, for example, a monitoring PC 12 and can constantly monitor the detection values output from the load cell 5 and the vibration sensor 11.

With such a wire saw device 13, at least one of the tension of the wire 8 detected by the load cell 5 and the vibration detected by the vibration sensor 11 is measured before cutting the work W, and this measured value is used. It is possible to judge whether the wire saw device 13 is normal or abnormal. Therefore, if the work W is cut when it is determined that the wire saw device 13 is normal, the deterioration of the quality of the wafer cut out from the work W can be prevented.

Next, a method of cutting the work of the present invention using the wire saw device of the present invention as described above will be described. Here, a case where the wire saw device 13 of the present invention shown in FIG. 1 described above is used will be described.

First, before cutting the work W using the wire saw device 13, while the work W is not in contact with the wire 8, the wire detected by the load cell 5 is repeatedly moved at least once forward and backward. At least one of the tension of No. 8 and the vibration detected by the vibration sensor 11 is measured, and a judgment step of judging whether the wire saw device 13 is normal or abnormal is performed by using the measured value. Then, when it is determined in this determination step that the wire saw device 13 is normal, a cutting step of cutting the work W is performed.

Specifically, as shown in the flowchart of FIG. 2, first, before cutting the work W, the wire 8 is made to travel forward and backward at least once in a state where the work W does not contact the wire row 9. This work is called warm-up operation (SP1). During this warm-up operation, at least one of tension and vibration is measured (SP2), and a judgment step (SP3) for judging whether the wire saw device 13 is normal or abnormal from the measured value (measured value) is performed. Then, if normal, the workpiece W is cut as it is (SP5) after the warm-up is continued (SP4). On the other hand, if abnormal, the wire saw device 13 is stopped (SP6), and maintenance such as replacement of the pulley P is carried out (SP7). After that, the warm-up operation is performed again (SP1), and this flow can be continued until it becomes normal.

At this time, in the determination step (SP3), control chart control (SP8) is performed using the measured value, and when the measured value is outside the control value limit, it is determined that the wire saw device 13 is abnormal (SP9). It is possible to stop the wire saw device 13 before cutting the work W and perform maintenance of the wire saw device 13 until it is within the control value limit, and then cut the work W.

In this way, by controlling the control chart, the state of the wire saw device 13 can be grasped before the cutting of the work W, and by performing maintenance in the case of an abnormal state outside the control value limit, the wafer cut out from the work W It is possible to reduce the quality deterioration and the occurrence of defects due to the quality deterioration.

As an example of determination of normality or abnormality, specifically, tension variation σ that can be calculated using the measured value of the tension of the wire 8 detected by the load cell 5 during one cycle of forward/backward movement during warm-up In addition, when the control chart control (SP8) is performed on the vibration amplitude that can be calculated using the measurement value of the vibration detected by the vibration sensor 11, the inside of the control limit line (within the control value limit) is normal or out of line ( There is a method (SP9) of judging that the value outside the control value limit is abnormal.

More specifically, after confirming that the standard deviation of the wire tension detected by the load cell is 0.45 N or less and the vibration detected by the vibration sensor is 1.0 mm/sec or less, The cutting can be done. That is, when this condition is satisfied, it is determined to be normal, and when it is not satisfied, it is determined to be abnormal.

According to the work cutting method using the wire saw device of the present invention as described above, it is possible to determine whether the wire saw device is normal or abnormal before cutting the work. Then, when it is determined that the wire saw device is normal, the work is cut, so that it is possible to prevent deterioration of the quality of the wafer cut from the work.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited thereto.

(Example 1)
Using the wire saw device of the present invention as shown in FIG. 1, the work was cut according to the work cutting method of the present invention. An ingot with a diameter of 300 mm manufactured by the CZ method (Czochralski method) was used as the work W.

First, before cutting the work W, the work 8 is detected by the load cell 5 while repeatedly traveling (warming operation) at least once forward and backward with the work W not contacting the wire 8 (wire row 9). The tension of the wire 8 was measured.

Then, control chart management of the tension variation σ calculated using this measured value was performed. FIG. 3 is a control chart of the tension variation σ during one cycle of forward and backward movement during warm-up. Each point in FIG. 3 indicates the tension variation σ during one cycle of forward and backward movement during warm-up. At this time, if the tension variation σ is within the control limit line (within the control value limit) of UCL (Upper Control Limit: upper control limit line) and LCL (Lower Control Limit line), the wire saw device is normal, If the wire saw is out of the limit (outside the control value limit), the wire saw device is judged to be abnormal. CL (Central Line) in FIG. 3 indicates the center line.

Then, when the tension variation σ as shown by the down arrow (b) in FIG. 3 is within the control value limit and it is determined to be normal, the work W is cut. The result of measuring the average Warp quality of 25 sliced products at this time is shown in FIG. SBW-330 (manufactured by Kobelco Kaken) was used for measuring the Warp quality. The error bar in FIG. 4 indicates the standard deviation (SD) of 25 Warp measured slices.

As a result, as shown in FIG. 4B, in Example 1, the Warp quality was 6.8 μm on average.

(Comparative Example 1)
As Comparative Example 1, when the variation in tension σ as shown by the downward arrow (a) in FIG. 3 is out of the control limit line and it is determined to be abnormal, maintenance is not performed and the work W is cut as it is. I went. The tension variation σ indicated by the lower arrow (a) in FIG. 3 was 0.46 N, which was outside the control limit line. The results of measuring the average Warp quality of 25 sliced products at this time are shown in FIG.

As a result, as shown in FIG. 4A, in Comparative Example 1, the Warp quality was 9.7 μm on average. As described above, since the work W was cut when the tension variation σ exceeded 0.45 N, the Warp quality deteriorated.

(Example 2)
Using the measurement value obtained by measuring the vibration detected by the vibration sensor, the average value of the vibration amplitude during one cycle of forward and backward movement during warm-up was calculated. Then, the work was cut in the same manner as in Example 1 except that control chart management was performed using the average value of the vibration amplitudes.

First, before cutting the work W, in a state where the work W is not in contact with the wire 8, the vibration detected by the vibration sensor 11 is repeated while the wire 8 is repeatedly moved forward and backward at least once (warm-up operation). The measurement was performed.

Then, control chart management of the average value of the vibration amplitude calculated using this measured value was performed. FIG. 5 is a control chart of the average value of the vibration amplitude during one cycle of forward and backward movement during warm-up. Further, each point in FIG. 5 indicates the average value of the vibration amplitude during one cycle of forward/backward movement during warm-up. At this time, it was determined that the wire saw device was normal when the average value of the vibration amplitude was within the control limit line (within the control value limit) of UCL and LCL, and abnormal when outside (outside the control value limit). In addition, CL in FIG. 5 shows a center line.

Then, when the average value of the vibration amplitude as shown by the down arrow (b) in FIG. 5 is within the control value limit and it is determined to be normal, the work W is cut. The average Warp quality of the 25 sliced products at this time was measured in the same manner as in Example 1, and the result is shown in FIG. The error bar in FIG. 6 indicates the standard deviation (SD) of the measured Warp of 25 sliced products.

As a result, as shown in FIG. 6B, in Example 2, the Warp quality was 7.1 μm on average.

(Comparative example 2)
As Comparative Example 2, when the average value of the vibration amplitude is out of the control limit line as indicated by the downward arrow (a) in FIG. 5 and it is determined to be abnormal, no maintenance is performed and the work W Was cut. The vibration at the position indicated by the lower arrow (a) in FIG. 5 was 1.2 mm/sec. The results of measuring the average Warp quality of 25 sliced products at this time are shown in FIG.

As a result, as shown in FIG. 6A, in Comparative Example 2, the Warp quality was 10.2 μm on average. As described above, since the work W was cut when the vibration exceeded 1.0 mm/sec, the Warp quality deteriorated.

From the above results, in the wire saw device before cutting the work as in the first and second embodiments of the present invention, the control chart is managed by using the measurement result of at least one of the vibration and the tension, and It was found that the state of the wire saw device can be grasped before cutting and the normal state within the control value limit can be maintained to reduce the quality deterioration of the work and the occurrence of defects due to the quality deterioration.

The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the invention having substantially the same configuration as the technical idea described in the scope of the claims of the present invention and exhibiting the same action and effect is the present invention It is included in the technical scope of.

Claims (4)

A wire supply reel that extends a wire, a wire row formed by the wires spirally wound around a plurality of wire guides, a wire take-up reel that winds the wire, and a work to be cut In a wire saw device having a work holding part for holding and performing cutting by pressing the work held in the work holding part against the wire row that travels at least forward and backward once or more,
A vibration sensor attached to the work holding unit, a load cell that detects the tension of the wire, and a normal or abnormal judgment of the wire saw device based on the detection result of the vibration sensor or the load cell before cutting the work. A wire saw device, comprising: a monitoring means for performing the operation . A method of cutting a work using the wire saw device according to claim 1,
Before the cutting of the work, the wire tension detected by the load cell and the vibration sensor are detected while the work is kept in contact with the wire and the wire is repeatedly run at least once forward and backward. A determination step of performing at least one of the vibrations of the wire saw and determining whether the wire saw device is normal or abnormal using the measured value.
A method of cutting a work, comprising a cutting step of cutting the work when it is determined that the wire saw device is normal. In the determination step,
Performs control chart management using the measured value, determines that the wire saw device is abnormal when the measured value is outside the control value limit, and stops the wire saw device before cutting the workpiece, The work cutting method according to claim 2, wherein the work is cut after performing maintenance of the wire saw device until the work value is within the control value limit. A method of cutting a work using the wire saw device according to claim 1,
Before the cutting of the work, the standard deviation of the tension of the wire detected by the load cell is 0.45 N or less while repeatedly moving the wire at least once forward and backward in a state where the work is not in contact with the wire. The method for cutting a work is characterized in that the work is cut after confirming that the vibration detected by the vibration sensor is 1.0 mm/sec or less.

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